Clean, wash and cut the leek into thick slices. Wash and halve the tomatoes. Put the sauerkraut in a sieve and drain. Whisk eggs and sour cream, season with salt, pepper and nutmeg
Pre-cook leek in salted water for about 2 minutes, then drain in a sieve. Heat 1 tablespoon of oil in a pan. Fry the sauerkraut for 3-4 minutes. Add leek, ham and tomatoes, season with salt and pepper. Put sauerkraut aside
Mix milk, salt, 4 tablespoons of oil and quark. Mix flour and baking powder and sieve over it. Knead to a smooth dough with the dough hooks of the hand mixer. Grease a tart mould (24 cm Ø, with lift-off base). Roll out the dough round (approx. 26 cm Ø), place in the form and press down. Spread the sauerkraut mix over it and pour the glaze over it. Bake in the preheated oven (electric range: 200 °C/ convection oven: 175 °C/ gas: level 3) on the lower rack for 30-40 minutes